Interlingua is a language developed by the International Auxiliary Language Association between 1939 and 1951 based on the international vocabulary in the major European languages and a minimal grammar for its use. The international vocabulary is the thousands of words having similar forms and the same meanings in at least three "source languages". These are English, French, Italian, Spanish/Portuguese and German and Russian, chosen because they lend extensively vocabulary to other languages, are heavy borrowers from other languages, or descend from a common source, which in this case is Latin or Vulgar Latin. There are thousands of international words. The forms of the words are objectively determined as the historic or theoretical ancestors nearest to all their modern variants, known as the prototypes. Because in most cases the prototypes are either Classical or Vulgar Latin, Interlingua is a kind of modern Latin with a vastly simpler, English-like grammar for westerners today. But other languages have contributed to the international vocabulary. Interlingua can be read at sight by most speakers of Romance languages, so Interlingua can be used as a bridge to the Romance languages. Because word formation in Interlingua is Latin in form, the thousands of Latin words in English are very similar to those in Interlingua. But Interlingua provides in most cases the Latin roots as ordinary verbs which are missing in English and non-Romance languages. Learning these verbs by using them in language opens up the ability to analyze meanings of Latin words both in English and Interlingua by using roots and affixes in Interlingua which are similar to those in English words. Those who learn Interlingua find that they can read Romance languages often with considerable understanding. And they have an increased vocabulary in English. So Interlingua is a means to greater word power in English and Romance languages. Interlingua is an excellent substitute for studying Latin if the main aim is to understand Latin words in English. The book introduces the reader to the simple grammar of Interlingua and also describes in greater detail, than any previous source, using numerous worked examples, the methods by which the international words were determined by objective methods. Each chapter of the book is accompanied by texts in Interlingua, both to read and to translate. In the chapters there is a piece on Alexander the Great from MacGuffey’s Reader, stories of school children visiting a museum, of families in their homes and at restaurants, of friends going shopping together, of people working together in a typical business, poker games on trans-Atlantic ocean-liners, a couple running out of gas, dealing with mechanics at a garage, and making an appointment with a doctor and visiting the doctor. Chapter 8 is a translation by the author into Interlingua from the Italian of Boccaccio’s Introduction to the Decameron, which concerns the Black Death that struck Florence in the early 14th Century. There are also exercises at the end of chapters covering topics in the chapter. There are also brief texts in English to translate into Interlingua. Translating from English to Interlingua is an exellent and rapid way to learn Interlingua. At the back of the book are two glossaries of 3248 words for translating from Interlingua to English or English to Interlingua. The words chosen in these glossaries are the most common in English and Interlingua. Because of the similarity of Interlingua’s grammar to that of English, the author introduces in each chapter first the explanation of a grammatical concept like nouns, pronouns, conjunctions, adjectives, adverbs, verbs, participles, tenses, moods, aspect and prepositions as these apply to English, and then provides descriptions of how the concept is similarly applicable in Interlingua. The book has an extensive Table of Contents and Index.